Air assisted formation method and apparatus



Sept. 1 5, 1964 HoRNBosTEL, JR 3,149,026

AIR AssIsTED FORMATION METHOD AND APPARATUS Filed Sept. 26. 1961 3 Sheets-Sheet 1 IN VEN TOR. lfaya' /omasfe! fn 1 a e AgoRNEi/s Sept. 15, 1964 L. HoRNBosTEL, JR

AIR AssIsTED FORMATION METHOD AND APPARATUS Filed sept. ze, 1961 3 Sheets-Sheet 2 ff ff f5 Sept. l5, 1964 HoRNBosTEL, JR

AIR AssIsTEn FORMATION METHOD AND APPARATUS Filed Sept. 26. 1961 3 vSheets-Sham 3 IN VEN TOR. fof/d brnasef Ji: L

A TTORNEYS United States Patent O 334%,926 All?. ASSESTED FGRMATEN METHGD AND APRARATUS Lloyd Hornhostel, Er., Beloit, Wis., assigner to Beloit Iren `Works, teieit, Wis., a corporation ot Wisconsin Filed Sept. 26, 196i, Ser. No. iitii 7 Siaims. (Ci. 162-268) The present invention relates to improvements in paper machines yand particularly to an improved method and mechanism for the improved removal of water and formation of a web from a layer of paper stock deposited on a travelling Fourdrinier wire.

In the formation of a paper web on a travelling framinous surface, such as aFourdrinier wire, a layer of paper stock is uniformly deposited on the moving surface from the head box, and the wire travels over table rolls and suction boxes for drainage of water from the layer to form the web. The stock issues from the head box beneath the slice lip and in deposition upon the moving Fourdrinier a large amount of water is flushed through the wire portion between the siice and the forming board, which is positioned directly after the breast roll. The drainage curve of the Fourdrinier represents a hyperbola with its highest value immediately after the slice lip and gradually decreasing toward the suction boxes where the curve becomes irregular due to the increased drainage at the suction boxes.

It has been discovered that due to the initial rapid iiush through the stock a iine mat of iibers is formed on the wire and the bers above the initial mat remain in suspension. This initial mat on the wire causes the drainage of water through the wire to decrease and consequently the activity of the fibers in suspension decreases. Fibers in non-active suspension tend -to occuiate and thus produce a non-uniform web or sheet of paper and occulation occurs as water drainage rate decreases.

A feature of the invention resides in the breaking up of the initial mat of iibers on the wire and the introduction in the stock of a iine scale agitation.

Methods have heretofore been used for the reduction of occulation and the prevention of the formation of an initial mat such as by the horizontal and vertical shakingl of the Fourdrinier table and the provision of lair jets above .the Fourdrinier table pointing down on the stock. These have not been fully satisfactory iri that shaking the Fourdrinier has the disadvantage of costly construction, power consumption, and a reduction of drainage at the table rolls. Air jets or showers above the wire have not been satisfactory mainly because or" their inability to penetrate the stock, and the stock has a tendency to accumulate on the showers above the wire resulting in lumps of fibers falling down on the stock with obviously undesirable results.

The present inventioncontemplates the provision oi a plurality of air jets directed upwardly against the lower surface of the wire bene-ath the stock provided in the conventional type forming board, land/ or provision of additional air jets along the Fourdrinier wire after the forming board. The air jets blow against the underside of the wire breaking up the above mentioned initial mat of fibers but do not penetrate or blow through the layer of stock, yand they simultaneously introduce or cre-ate a hill and valley pattern in the stock on the wire which will tend to continue over the length of .the Fourdrinier. Due tothe up and down motion of this pattern, the pumpving action of the table rolls will be increased which is of Accordingly, an object of the invention is to provide a method yand apparatus which will successfully break up the initial fine matof iibers formed next to the wire below the layer off stock deposited on -a travelling forming wire, and which will result in van increase of drainage ot water from the layer of stock.

A still further object of the invention is to provide a method and mechanism which will prevent the cessation oi stock -activity yin the layer of stock on the wire and will actually provide an increase of stock activi-ty and a decrease in the occul-ation resulting in an improved paper web.

A still further object of the invention is to provide an improved method and apparatus for dewatering a paper web on -a foraminous travelling surface which is par-tief ul-arly well suited to making heavy paper, and which obtains an increase in the ratio of the cross direction to machine direction strength ratio of 4the formed sheet and permits an adjustment of this ratio.

Other objects, advantages and features will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiments thereof in the specitication, claims and drawings, in which:

FIGURE 1 is a side elevational view shown in somewhat schematic form of the forming section of a paper machine constructed in accordance with the principles of the present invention;

FIGURE 2 is a fragmentary top plan Viewl las viewed substantially along line ll-II of FIGURE l;

FIGURE 3 is an enlarged detailed elevational view of an air supply tube;

FIGURE 4 is a vertical sectional View taken substantially `along line IV-IV of FIGURE 3;

FlGURE 5 is a vertical sectional view similar 4to FIG- URE 4 yand illustrating a structure providing plural rows of jets in a single tube;

FIGURE 6 is a schematic illustration of the formation of an initial mat from a layer of stock on a forming wire;

FIGURE 7 is an enlarged fragmentary detailed view of a portion of the yforming board of FIGURE l;

FiGURE 8 is a fragmentary vertical sectional view illustrating the prol'e of the layer of stock in a cross direction due to the staggered arrangement of jets; and

FIGURE 9 is an enlarged schematic view illustrating the resul-tantV action on fibers ina cross direction due to the action of the air jets. Y

As shown on the drawings:

FGURE l illustrates a portion of the Fourdrinier machine with a travelling wire 10 and a layer of stock L deposited .thereon and being dewatered to form a paper web. The layer is deposited from a head box l1 having a slice 12, and positioned above a breast roll 13 supporting' the Fourdrinier wire 10. The layer of stock ows beneath the'slice 12 onto the wire 10 and across a. forming board llt. The upper surface of the forming board has a series oflaterally extending rows ofl air emission openings or air jets 15, 16 and 17, FIGURES l and 2. Between the rows of .air jets are laterally extending rows oi drain openings 13 and 19. The air jet openings are laterally staggered from the openingsin previous rows as illustrated in FIGURE 2, tor purposes which will later be described. Also, the .drain openings may be positioned 3 fold headers 21, FIGURE 7, beneath the jets, communicating with the openings such as 15 through openings 22a in a plate 22 below the top plate 23 of the forming board 14. The top surface of the forming board 14 is smooth for supporting the Wire, and the forming board is adjustable in vertical and horizontal directions' on its support as indicated by the arrowed lines 23a of FIGURE l.

Water drains out through the drain openings such as 18 in FIGURE 7, and through openings in the plate 22 down into a water drain box section 24 and out through a drain line 25. Suction is applied to the drain line 25 to create a partial vacuum within the box section 24 and a pressure differential across the layer of stock L at the drain openings 18 and 19.

In operation, with respect to initial drainage, as the stock issues from beneath the slice 12 and is deposited upon the Fourdrinier wire 10 a large amount of water is fiushed through the wire portion between the slice and the forming board and this .tends to form an initial fine mat of paper fibers on the wire as illustrated at 26 in FIGURE 6. The fibers at 27 in the layer L remain in suspension but the formation of the initial mat 26 causes the drainage of the water through the wires to decrease and consequently the activity of the fibers in suspension at 27 decreases. As the fibers lose their activity they tend to fiocculate which .is undesirable and forms a non-uniform paper sheet. When the layer L reaches the first row of air jets I on the forming board 14, the jets raise the layer L above the wire to break up the initial mat 26 of fibers and to also introduce in the stock fine scale agitation. The raised portion 28, FIGURE 7, again lowers against the wire at 29 above the drain opening 18. This formation of a slight hill or ripple in the layer L is repeated as the layer passes' over the air jets 16 and then reaches the drain openings 19, and -then passes t the air jets 17, FIGURE 2.

The air jets are shown as preferably directed in a angle toward the oncoming wire 10 with the 4angle being shown at a, and this angle is preferably 30 with respect to a line drawn vertical to the wire, or in other words at a 60 angle to the Wire.

FIGURE 8 illustrates the effect on the layer of stock L due to the staggered arrangement of the air jets. The raised por-tions of the layer L are shown raised in FIG- URE 8 for illustration, and the raised portions 30, for example are being caused by the air jets While the raised portions 31 are ahead of it, being caused by the-air jets 16 and staggered with respect thereto. This insures breaking of the initial mat at the base of the layer uniformly across the layer and improves-the activity of the fibers and their eventual orientation in lthe finished paper sheet.

FIGURE 9 illustrates the action of the raised portions of the layer of stocks with the figure being exaggerated in size to illustrate the fiber action, .and being taken as looking at the layer in section taken across the machine. The rises 32 in the layer of stock introduce a hill and valley pattern so that fibers originally aligned in the direction of travel of the web or machine direction (MD) will be forced to realign and will iiow in the direction of the arrows 33 in the cross machine direction (CD). The fibers in effect run downhill and the lateral spacing of the air jets, and the staggering of the air jets, givesV more of a cross machine fiber orientation to the finished sheet. This results in an increase in the CD/ MD strength ratio of 4the formed sheet. can be obtained' by varying the air pressure to the air jets.

Thev hill and ,valley pattern inthe layer of stock on the wire will continue over the length of the Fourdrinier, anddue to the up and down motion will increase the pumping action of the table rolls. vThis is of great. importance on low speed machines since the pumping action of the table rolls is proportional to the square of the machine speed.

Further, adjustment of this ratio Following the forming board, beneath the wire 10, are a series of table rolls, as illustrated by the roll 34. The table rolls are followed by suction boxes, and the structure of these, as Well as the remaining structure of the Wire and its support need not be shown since they will be apparent to those versed in the art.

Similar results for enhancing the formation of the web and improving draining can be obtained by providing air jet tubes 35 and 36 to provide air showers beneath the wire 1t) as illustrated in FIGURES 1 and 3. The air shower tubes will extend longitudinally across the wire and will be supported at their ends in mounts 37 and 37a on the frame 38 of the machine. Air is supplied through an air supply line 39 from a pressure source 48 through a pressure control valve 41. By change of air pressure the height of rises in stock above the web can be controlled to a desired amount and increase in height will increase the cross flow of fibers.

Individual jets for the air showers are formed by spreading the tube 35, FIGURE 4, with the material 42 of the tube turned outwardly in flanges 43 and 44, and axially separated spacers 45 placed between the anges and held therein by spot welds 46. The open areas between the spacers 45, as defined by the flanges 43 and 44, form air jets.

In FIGURE 5 the material of the tube 47 is opened at two locations to form rows 43 and 49 of jets. The jets are laterally staggered by placing spacers 50 and 51 in staggered arrangements, and attaching the spacers in the same manner of the structure of FIGURE 4.

It will be understood that the air shower tubes 35 and 36 may be used in addition to the forming board arrangement illustrated and described in FIGURES l and 2, or the boards may be used independently. Air showers may be placed between table rolls over the entire length of the Fourdrinier if desired, or at a ny part thereof. FIG- URE l is selected to show both an air jet forming board and a tube with a single row of jets and a tube with plural rows but the arrangement and sequence is shown merely to illustrate the various forms of air jet means.

The air shower tube 35, FIGURE 3, may be connected to a simple shake mechanism, shown schematically by the arrowed line 52, FIGURE 3, which gives the tube an axial shaking movement for varying the effect on the web and improving the cross direction orientation of fibers in the finished sheet.

In brief summary of operation, paper stock flows in a layer L from a head box onto the wire 1t), and on the forming board 14 rows of air jets 15, 16 and 17 with alternate suction drainage openings 18 and 19 form hills andv valleys in the layer of stock breaking up the initial mat 26, FIGURE 6, of fibers which is formed, causing a fine scale agitation of the fibers and improving drainage. This action continues in the surface of the web along the Fourdrinier and may be enhanced by the provision of air shower tubes 35 and 36 between the table rolls 34.

Thus it will be seen that I have provided an improved paper forming machine which meets the objectives, advantages and features above set forth. The method and operation of the mechanism avoid disadvantages of attempts of prior art devices to accomplish the result, and a mechanism is provided which achieves an' improved paper product.

The drawings and specificationV present a detailed disclosure of the preferred embodiments ofthe invention, and it is to be understood that the invention is not limited to the specific forms disclosed, but covers all modifications, changes and alternative constructions and methodsr falling within the scope of the principles taught by the invention.

I claimas my invention:

1. In a Fourdrinier paper machine, a travelling Fourdrinier forming wire, means for depositing a layer ofpaper stock on the top surface of the wire, a first plurality of air jets extending laterally across beneath the wire and directed upwardly, and a second plurality of air jets longitudinally spaced from said first plurality of air jets extending laterally across beneath the wire after said first jets and staggered laterally with respect to the first jets to inhibit the flocculation of the paper stock on the wire without penetrating the layer of stock.

2. The method of improving web formation from paper stock deposited on a foraminous moving surface subjected to a pressure differential thereacross for removing Water downwardly through the surface, which comprises directing discrete streams o-f air beneath said forming surface across the Width of the forming surface tending to raise the layer of stock at the locations of the streams without penetrating the layer of stock.

3. The method of improving web formation from a deposited layer of paper stock on a travelling Fourdrinier wire comprising directing discrete jets of air at longitudinally spaced laterally staggered locations across the Wire upwardly through the wire raising the stock at said locations Without penetrating the stock effecting changes in the horizontal plane of the layer of stock for shifting of fibers for improved orientation and inhibiting occulation of fibers of the stock.

4. A mechanism for forming a paper web from stock deposited on a moving foraminous surface With a water draining pressure differential thereacross comprising a plurality of discrete air jets beneath the foraminous surface spaced laterally across the surface, means for supplying air to the jets, and means for adjustably controlling the pressure of the air to adjust the height of rises in the stock at the jets and the cross orientation of paper fibers without penetrating the stock.

5. In a paper machine, a moving foraminous paper forming surface, means for depositing a layer of paper stock on said surface, and means for directing separate small discrete streams of air onto the undersurface of the moving forming surface tending to raise the layer of stock and improving web formation without penetrating the layer of stock, said streams separated laterally across f5 the forming surface and longitudinally to form separate hills and valleys separated in a lateral and in a longitudinal direction.

6. A machine for forming a paper web comprising a moving foraminous paper forming surface, means for depositing a layer of paper stock on said surface, and means for directing individual small discrete streams of air upwardly on the undersurface of said layer of stock without penetratiang the layer of stock across the Width of the forming surface at an angle against the movement of the forming surface.

7. The method of forming a paper web from stock deposited on a moving foraminous web forming surface which comprises alternately raising the layer of stock before the stock has been devvatered to an extent to x the relative position of the bers and the fibers are still in suspension at predetermined separate locations across the width of the forming surface above said surface and lowering the stock to the surface to cause a shifting of fiber deposition on the surface, and applying a pressure differential across the surface for drawing Water downwardly from the layer of stock, such raising of the layer of stock being effected by directing discrete streams of air beneath said forming surface across the width of the forming surface tending to raise the layer of stock at the locations of such discrete streams Without penetrating the layer of stock.

References Cited in the file of this patent UNITED STATES PATENTS 1,549,338 Tompkins Aug. 11, 1925 2,073,654 Smiley Mar. 16, 1937 2,345,647 Witham Apr. 4, 1944 2,995,186 De Montigny Aug. 8, 1961 FOREIGN PATENTS 667 Great Britain of 1879 665,034 France Apr. 30, 1929 500,956 Germany July 19, 1930 

2. THE METHOD OF IMPROVING WEB FORMATION FROM PAPER STOCK DEPOSITED ON A FORAMINOUS MOVING SURFACE SUBJECTED TO A PRESSURE DIFFERENTIAL THEREACROSS FOR REMOVING WATER DOWNWARDLY THROUGH THE SURFACE, WHICH COMPRISES DIRECTING DISCRETE STREAMS OF AIR BENEATH SAID FORMING SURFACE ACROSS THE WIDTH OF THE FORMING SURFACE TENDING TO RAISE THE LAYER OF STOCK AT THE LOCATIONS OF THE STREAMS WITHOUT PENETRATING THE LAYER OF STOCK. 